Peristaltic pumps are well known in the art. These pumps usually consist of a base member having at least a portion of a generally cylindrical surface, a rotatable shaft located coaxially along the axis of said cylindrical surface, and several rollers supported by said shaft and positioned for movement along a predetermined circular path near the cylindrical surface. In U.S. Pat. Nos. 3,289,232 and 3,447,478 the base member is spring biased toward a pumping position and movable against said bias toward a non-pumping position. An elastically deformable tube having an inlet and an outlet is positioned between the cylindrical surface of the base member and the rollers in such manner that when the base member is in pumping position the elastically deformable tube is deformably closed by the rollers whenever the rollers come in contact with the tube. As the shaft is rotated, the rollers move along the tube and create a peristaltic pumping action. The tube is anchored in at least one point along its length so as to prevent gross tube movement through the pump.
These prior art pumps had several disadvantages. First, the only way of stopping the pumping action was by moving the base member to non-pumping position, where possible, or by stopping the movement of the pumping rollers along the pump tubing. While movement of the base member to non-pumping position effectively stops the pumping action, it does not provide a positive shut off of fluid flow through the pump. Stopping the rollers creates a problem in a multiple channel pump, since the pump rollers are common to all channels and it may be desired to stop or start the pumping in one channel independent of the other channels. Second, the prior art pumps usually start the pumping action by starting the movement of the pump rollers, irrespective of their position along the pump tubing. This can cause an undesirable variation in fluid pumped in a given unit of time and is especially undesirable when relatively small quantities of fluids are being pumped.
These disadvantages of prior art peristaltic pumps are overcome by the pump of the present invention.